Darren Osborne was driven by anti-Muslim hatred. The 48-year-old, who was found guilty of the murder of Makram Ali and attempted murder of several others, had rammed his van into worshippers outside the Muslim Welfare House last June. We know that the unemployed father-of-four had been swiftly radicalised online. His case outlines what many of us have been warning about and seeing through our work with national projects countering anti-Muslim hatred.

The rise in anti-Muslim hatred is a scourge that makes none of us safer. It creates fear within Muslim communities, polarises opinions, pushes perceptions and hearts and minds into the hands of Islamist groups and then further strengthens the anti-Muslim rhetoric pushed by far-right extremist groups – some of which Osborne fed from. We are shown, graphically, that anti-Muslim hatred needs to be tackled at every level, since such hatred strengthens and polarises all of the extremes in our society.

For far too long social media companies have taken little action against Islamophobia

Osborne was radicalised after watching a TV drama about the Rotherham grooming scandals. Such was his anger, it seems, that he searched out and ultimately consumed extreme anti-Muslim material, which has become a cottage industry for supporters of groups such as the English Defence League and Britain First, whose online presence Osborne sought out.

And the impact of such hate is clear to see. English Defence League founder Tommy Robinson stated militias could be set up to “clean out this Islamic problem” barely weeks before Darren Osborne’s attack. Anti-Muslim rhetoric and hatred online can tip unstable and vulnerable people over the edge. Like Thomas Mair who murdered Jo Cox, Osborne was self-radicalised. In Osborne’s case it was extremely rapid – within a month – and largely happened online. He took the same journey and talked the same kind of language (demanding to be martyred by the angry crowd after his attack) as the jihadi wannabes he so despised, drawn in by charismatic and web-savvy ideologues.

For far too long social media companies have taken little action against Islamophobia. For years, I have challenged Twitter and others to remove anti-Muslim material from their feeds. Their mantra seems to have been that free speech will allow good to triumph over evil. This has the benefit of diverting attention and responsibility from themselves, but it will not wash any more. The Osborne case makes clear that social media firms cannot shirk their responsibilities. They must remove such hateful material, whether it be anti-Muslim or antisemitic.

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Summing up after the guilty verdict on Osborne, Justice Hayden said: “We have to be alive to the fact that people are accessing this [extremist] material and they are using it to self-radicalise and that’s what happened in this case. My view is I think internet companies could do more to be proactive in relation to taking the material down themselves.”

Osborne will now go to prison. Those who inspired him, produced hateful anti-Muslim material and those platforms which carried that and failed to remove it, go unpunished. They should hang their heads in shame. How many lives are going to be lost before we take action against these online pedlars of hate? And how many will be lost while social media companies talk about “free speech” and continue to cash in on advertising at society’s expense?

• Fiyaz Mughal is founder and director of Faith Matters and the founder of Tell MAMA, the national project monitoring and assisting victims of anti-Muslim hatred.